Activity for the hydrolysis of maltose 6 phosphate [maltose 6P] has been stabilized in sonic extracts of maltose grown Fusobacterium mortiferum (ATCC 25557) using dithiothreitol [DTT]. All of the activity was found in a single protein with a molecular weight of 49 KD following purification in the presence of DTT and assay with an artificial alpha glucoside phosphate. The purified protein hydrolyzed authentic maltose 6P to equimolar amounts of glucose 6P and glucose confirming a phosphoenolpyruavate phosphotransferase (PTS) activity for maltose use by F. mortiferum. The hydrolytic activity of maltose 6P hydrolase was restricted to alpha glucoside phosphates and required Mn++. An artificial alpha glucoside phosphate proved necessary for the purification of the protein and an antibody was made to the resultant 49 KD homogeneous protein with enzyme activity. Maltose 6P hydrolase activity was induced in F. mortiferum by growth on a variety of sugars; mostly, but not exclusively, alpha glucosides. The specific activity of the hydrolase enzyme was proportional to a hierarchy of growth sugars and the activity was exclusively in a 49 KD protein. The sequence of 32 amino acids from the NH2 terminal end of the maltose 6P hydrolase was determined and the activity was cloned, sequenced, and expressed in Escherichia coli. Growth on beta glucosides induced the anaerobic use of cellobiose by washed cell suspensions of F. mortiferum. A 54 KD protein with activity for the hydrolysis of a beta glucoside phosphate has been purified and identified from sonic extracts of cellobiose grown cells. The properties of this beta glucoside phosphate hydrolase and its functioning in a cellobiose PTS in F. mortiferum are now being studied. Maltose is used by F. necrophorum, but by a different mechanism than that reported by us for F. mortiferum. The 49 KD protein for the maltose 6P hydrolase could not be demonstrated in a sonic extract of maltose grown cells of F. necrophorum. Two strains of Streptococcus mutans, reported to have a maltose PTS, had no detectable activity when sonic extracts were tested with antibody to the F. mortiferum maltose 6P hydrolase.